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• June 17, 2005 | 6:15 p.m. ETThe realities behind quake risks: Just because California has weathered
four significant quakes in a week
doesn’t mean the Big One is on the way, seismologists say. In fact, they say the chances that a bigger quake is coming are about the same as they are after every seismic event.

"Every earthquake that happens, there is a 5 percent chance that it will be followed by a bigger one," said Karen Felzer, a geophysicist with the Earthquake Hazards Team at the U.S. Geological Survey in Pasadena, Calif.

Scientists say this week's quakes are actually better thought of as two pairs: Tuesday's magnitude-7.2 undersea quake and Thursday's 6.6 aftershock in Northern California, and the 5.2 and 4.9 quakes in Southern California. The two southern quakes weren't as closely related as the northern quakes, Felzer said, but it could be that one "triggered" the other.

Although making links between the quakes is by no means an exact science, seismic activity does follow a statistical model known as a power law, Felzer said. (So do
best-seller lists
and the blogosphere, by the way.)

The linkage between earthquakes "basically decays with distance about as quickly as it decays with time," she said. "What we don't know right now is where that decay stops."

Obviously, the quake risk never goes down to zero. "We have a slightly increased chance around the places we've been having them in the last few days, and that's part of life here," Lucy Jones, scientist-in-charge for the Earthquake Hazards Team, told NBC's "Today" show.

But the power-law relationship could be used to argue that every quiet day after a significant shaking makes a related follow-on earthquake less likely.

"Today there's a lot more risk than tomorrow," Felzer said. "The risk you see on the first day is roughly the same as what you're going to see cumulatively over the following 10 days. Then, after you get past that, you're looking at the next hundred days. Over the next hundred days, the cumulative probability is the same as it was over the 10 days."

For that reason, the USGS’ earthquake hazard forecast map sprouted some yellow spots immediately after each of this week's quakes to reflect a heightened risk, but has since subsided to soothing blue and green colors.

Video: Quake analysis
As of today, there was just the barest hint of yellow between Los Angeles and San Diego, and near Eureka in the north. That would translate into a roughly 1 percent chance of a shaking strong enough to throw objects off shelves sometime in the next 24 hours.

As you might expect, the forecast Web site — which was
unveiled just last month
— became quite a popular online destination during this week's tremors.

"The peak looks like 4,000 hits per second," Felzer said, "but then it decayed quickly with time ... just like the aftershocks did."

• June 17, 2005 | 7:25 p.m. ETPlenitude of planets: This weekend is the beginning of prime time for planet-watchers. If the western horizon is clear just after sunset, you can spot three planets in the twilight: bright Venus, medium Saturn and faint Mercury. The planets shift into a tight trio during the June 24-27 time frame, then go their separate ways until Saturn disappears from view in early July. Check out Sky & Telescope's news release and particularly its video sky guide (QuickTime required) to get a fix on the celestial threesome.

Meanwhile, Jupiter hangs out in the night sky and can serve as a guide for finding Comet Tempel 1, the target for Deep Impact's July 4
cosmic crack-up
. Just before sunrise, Mars is visible in eastern skies.

Looking beyond our own solar system, NASA is gearing up to announce scientific findings from the Hubble Space Telescope, supporting the view that a planet is forming around Fomalhaut, a star just 24 light-years away. Stay tuned for the full story on Wednesday.

• June 17, 2005 | 7:25 p.m. ETBlue Origin opens up: As reported here earlier this week, the space venture backed by Amazon.com founder Jeff Bezos has been providing more information about its spaceport plans during a series of public meetings in West Texas. Seattle-based Blue Origin hopes to begin flight tests in late 2006 — and according to updates from the Van Horn Advocate and Space.com, the testing phase is expected to last three to five years, with less than 25 flights planned per year. The vertical-takeoff, vertical-landing spaceships would reportedly be assembled in Seattle and trucked down to Texas for launch.

This week's meetings were aimed at gathering feedback to support Blue Origin's launch application to the Federal Aviation Administration's Office of Space Transportation. About 50 people attended the initial meeting in Van Horn, according to the Advocate.

• June 16, 2005 | 8:45 p.m. ET50 years of seeing atoms: Modern masters of the microscope are gathering at Penn State University this week to mark the 50th anniversary of the first atomic-scale observations — and look to the future as well.

Back in 1955, a team led by Erwin W. Müller used a device known as a field ion microscope to identify single atoms, based on their mass. Müller's work in microscopy went back to the 1930s, when he invented a forerunner called the field emission microscope. Today, you need a field guide to keep all the different technologies straight.

This isn't a purely academic pursuit: To cite just one example, the local-electrode atom probe developed by Wisconsin-based Imago Scientific Instruments analyzes the 3-D atomic composition of semiconductor samples at resolutions of less than a nanometer by collecting data at a rate of a million atoms per minute.

That's valuable information for semiconductor manufacturers. As electronic circuits become more and more miniaturized, the manufacturers have to lay down layers of materials that may be just a few atoms thick, said Tom Kelly, the company's founder, chairman and chief technology officer. How low can you go before fabrication flaws trip you up?

"Being able to see what you're doing is an essential part of doing anything," he told me during my visit to Madison.

The samples are prepared for analysis by paring them down to an ultra-fine point, then using a powerful, focused electric field to pull the individual atoms apart. Imago's software analyzes the pattern of emissions and reconstructs a 3-D image. The technique can be applied to data-storage devices, metallurgical analysis and more.

"It doesn't have to be a semiconductor wafer," Kelly said. "It could be a frozen cell."

Unraveling the structure of organic molecules — say, proteins — would be a new killer app for atomic-scale microscopy. "There's good reason to believe we will get there, but it's not going to happen tomorrow," Kelly said.

• June 16, 2005 | 8:45 p.m. ETBack from stem-cell mecca: Most of my stay in Madison was devoted to learning more about human embryonic stem cells and the deep debates surrounding their application, as part of a fellowship program sponsored by the University of Wisconsin and the WiCell Research Institute. There'll be a lot of activity in the weeks ahead, on the
political front
as well as the scientific front, so you can look forward to in-depth reporting on stem cells and the social implications here on MSNBC.com.

In an evening landscape from NASA's Spirit rover, the sun nears the Martian horizon, causing a blue glow above.

This picture, sent from the Columbia Hills back to Earth by NASA's Spirit rover on May 19, is one of several Martian
sunset
(and
sunrise
) pictures that help scientists figure out the composition of the planet's dusty atmosphere. The blue glow is due to light diffracted by ice crystals — the same sort of diffraction that makes the whole daytime sky blue here on Earth.

In its photo advisory, NASA's Jet Propulsion Laboratory provides a more detailed explanation of the scientific point behind the pretty pictures:

"Sunset and twilight images are occasionally acquired by the science team to determine how high into the atmosphere the Martian dust extends, and to look for dust or ice clouds. Other images have shown that the twilight glow remains visible, but increasingly fainter, for up to two hours before sunrise or after sunset. The long Martian twilight (compared to Earth's) is caused by sunlight scattered around to the night side of the planet by abundant high-altitude dust. Similar long twilights or extra-colorful sunrises and sunsets sometimes occur on Earth when tiny dust grains that are erupted from powerful volcanoes scatter light high in the atmosphere."

The Spirit and Opportunity rovers aren't the first robotic emissaries to watch a Martian sunset; you can check out a 29-year-old classic from the Viking 1 lander, as well as some cool views from Mars Pathfinder in 1997. For a visual explanation of the blue-sky effect (on Earth as well as Mars), check out our archived
story
and
interactive
on the subject. And for a view of the good old Stars and Stripes on Mars, you need look no further than our
Mars' greatest hits slide show.

• June 14, 2005 | 8:45 p.m. ETPrivate-sector space in spotlight: As
expected
, NASA announced a deal today to use Zero Gravity Corp.'s service for two weightlessness-simulation flights in September. The space agency says it still intends to fly its C-9 successor to the "Weightless Wonder" (also known as the "Vomit Comet") for zero-gravity research flights later in the year. Nevertheless, the fact that Zero-G will be conducting demonstration flights for NASA is a plus for the company's founder,
Peter Diamandis
, who is also the chairman of the X Prize Foundation.

Meanwhile, The New York Times highlights the "Thrillionaires" behind what Diamandis has called the personal spaceflight revolution in an article today (registration required). Consultant Charles Lurio, who was quoted in the story, has sent out a "footnote" predicting that space tourism won't always be just for the super-rich:

"Certainly in these early days some of the ‘New Space’ ventures are being funded by single super-rich investors. And the initial price of commercial suborbital rides will be pretty pricey (say, $100,000 to $250,000 per person) until the learning curve kicks in. But to date, spaceflight has largely been the purview of companies that amount to ‘captive’ government design bureaus, and we know how many taxpayer billions have been uselessly burned there.

"So if the self-selected rich and well-to-do — instead of all taxpayers — end up paying the initial price for finally bringing normal market discipline and vastly lower prices to access to suborbit, orbit and beyond for all humanity — well, that strikes me as better than a good deal.

• June 13, 2005 | 2 a.m. ETSpace secrets go public: Blue Origin, the usually hush-hush space travel company backed by Amazon.com founder Jeff Bezos, is revealing more about its plans in advance of public meetings scheduled this week in West Texas, where the venture intends to build its spaceport.

A Cosmic Log correspondent points to the Van Horn Advocate's advance notice of the meetings on Tuesday and Wednesday, as well as an "Executive Summary" Web page that lays out some previously little-known details about Blue Origin's intentions (Thanks, Jim!).

Last January, Seattle-based Blue Origin announced it would
set up a test facility
on part of a 165,000-acre spread that Bezos owns near Van Horn. On the Web page, the company says it aims to begin developmental test flights in the third quarter of 2006.

If the tests are successful, the vertical-launch, vertical-landing spaceship could fly as many as 52 suborbital space missions per year from the West Texas facility. Each flight would go to an altitude of more than 325,000 feet, with three or more passengers, Blue Origin says:

"The Blue Origin RLV [reusable launch vehicle] would be comprised of a propulsion module and a crew capsule and would use hydrogen peroxide and kerosene as propellants. The RLV would be fully reusable and would operate autonomously under control of on-board computers, with no ground control during nominal flight conditions. The RLV would launch vertically from a concrete pad and would land vertically in an area near the launch pad."

Key Blue Origin staff members will take questions from the public at this week's West Texas meetings, in Van Horn on Tuesday and in Dell City on Wednesday, according to the Advocate. They'll also explain the process for moving forward with their plans, which will require an environmental assessment as well as a launch operator license from the Federal Aviation Administration's Office of Commercial Space Transportation.

Blue Origin is something of a wild card in the space travel game. Other players are placing their own bets that they can begin taking on suborbital space passengers in the next few years:
Virgin Galactic
was the first to announce its intentions, with flights due to begin in 2008.
Aera Corp.
says it's aiming to start commercial flights in 2006-2007, although details on funding are scant. And
PlanetSpace
is aiming for service to begin in mid-2007.